Electric transport character in the La0.7Ce0.3MnO3–SrTiO3–Nb heterojunction

The electric transport character in heterojunction composed of a La0.7Ce0.3MnO3 film and a 0.5 wt% Nb-doped SrTiO3 substrate (LCEM/STON) is investigated. It is found that the energy band gap (Eg) between LCEM and STON decreases with increasing temperatures. The most striking observation of present work is that there exists a variation of reverse transport mechanism from ionization to tunneling at the temperature of 175 K. We attribute the temperature dependence of reverse transport mechanism to co-work of Eg and the ferromagnetic (FM) insulting phase in the heterojunction. These results are helpful in configuring artificial devices using manganites.